BMW 63128386047 Left Headlight Assembly

If a car has an operational only high beam or low beam headlight, there will be battery voltage at the headlight electrical connector; change the headlight assembly or bulb where there is available. If voltage is not present the problem must be worked out according to the headlight wiring diagram. If the headlight does not work both high or low beam then apply voltage and ground at the headlight electrical connector. If voltage is present, check also the headlight connector ground terminal for a good connection to ground. If battery voltage and ground are present the repairer should replace either the headlight assembly or bulb if can be done separately. If headlight voltage failed or if head light ground failed then check the wiring diagram of headlight. Also, check and test the headlight switch and replace it if it has a bad or malfunctions in its performance. When lights are very poor or non existent, test for battery voltage and ground at the headlight electrical terminal. In case there is voltage present, check the ground circuit for the headlamp electrical connector and clean and repair as the case may be. If the voltage at this point if lower than that of the battery attach a multimeter between the headlight electrical connector and the headlight wiring diagram to determine the position where the voltage dropped.